Storage area networks (SANs) are typically implemented to interconnect data storage devices and servers or hosts, using network switches to provide interconnectivity across the SAN. SANs may be complex systems with many interconnected computers, switches, and storage devices. The switches are typically configured into a switch fabric, and the hosts and storage devices are connected to the switch fabric through ports of the network switches that comprise the switch fabric. Most commonly, Fibre Channel (FC) protocols are used for data communication across the switch fabric, as well as for the setup and teardown of connections to and across the fabric, although these protocols may be implemented on top of Ethernet networks.
Many SANs rely on the FC protocol. The FC protocol defines standard media and signaling conventions for transporting data in a serial fashion. It also provides an error correcting channel code and a frame structure for transporting the data. Many FC switches provide at least some degree of automatic configurability. For example, they may automatically sense when a new inter-switch link (ISL) becomes active, and may initiate an initialization process to discover what the link connects to. The switch may automatically determine various parameters for the link (e.g. link speed). As FC networks are created, updated, maintained and de-commissioned, switches may be enabled, disabled or reconfigured, and links may be added or removed.
Over time, FC networks have become more complex, with multiple fabrics involving several switches that use inter-switch links (ISLs) connected to switch ports (E_ports) on the switches. At the same time as FC networks have become more complex; the network speeds have also increased significantly. As faster networks are implemented, media and cable tolerance become more important for avoiding degraded performance and cyclic redundancy check (CRC) errors. As larger networks are developed, diagnosis of optics and cables become more and more time consuming and intrusive. Current switches have two basic types of built-in diagnostics. First, the SFP electro-optical modules have digital diagnostics, but these only operate at the SFP component level. Second, a command line interface (CLI) tool may be provided to allow frames to be injected and circulated on a specific link, but the end result is only a good and bad indication, which does not greatly aid diagnosis. A third method of diagnosing ISL errors is to use D-ports, as discussed in U.S. patent application Ser. No. 13/047,513, the entire disclosure of which is hereby incorporated by reference. The D-port system would require that two ports be taken offline while the system performs the desired diagnostics. As such it is not useful for performing online diagnostics. Thus, troubleshooting suspected link and path errors with the existing tools is time consuming, can become a daunting task and/or requires that taking some ports offline. The use of external separate testing tools is also cumbersome and brings along separate problems not present with built-in tools.
Thus, it would be desirable to implement an efficient network diagnostic method to more efficiently troubleshoot larger networks, thereby improving the speed, efficiency, and reliability of these networks.